CN104944448B

CN104944448B - Preparation method for needle-shaped magnesium hydroxide

Info

Publication number: CN104944448B
Application number: CN201510342011.2A
Authority: CN
Inventors: 钱海燕; 姜露露
Original assignee: Nanjing Tech University
Current assignee: Nanjing Tech University
Priority date: 2015-06-18
Filing date: 2015-06-18
Publication date: 2017-01-18
Anticipated expiration: 2035-06-18
Also published as: CN104944448A

Abstract

The invention provides a preparation method for needle-shaped magnesium hydroxide. The preparation method comprises the following steps: (1) calcining magnesite to obtain undercalcined magnesia; (2) mixing the undercalcined magnesia, water and a magnesium salt dispersing agent to obtain a suspension, stirring for reaction, then adding seed crystal, and leaving the mixture to stand; (3) reducing the temperature to the room temperature, and aging; (4) filtrating, washing and drying to obtain needle-shaped magnesium hydroxide. The preparation method has the advantages that the raw materials are easy to obtain, the process is simple, a hydro-thermal treatment procedure in a conventional hydration method is eliminated, the energy consumption is reduced, and the preparation method is suitable for industrialized production; needle-shaped magnesium hydroxide with different length-diameter ratios can be prepared by changing process conditions such as the type of the dispersing agent, concentration, hydration temperature, time, aging time and the like; the prepared magnesium hydroxide can be used as seed crystal to be recycled, so that the production cost is reduced.

Description

The method preparing acicular magnesium hydroxide

Technical field

The invention belongs to inorganic particle technical field is and in particular to the method for preparing acicular magnesium hydroxide by aquation method.

Background technology

High molecular synthetic material is widely used in daily life, its flammable safety becoming production, life with inflammability Hidden danger, carrys out the probability of fire to reduce composite material tape, the concern of flame-retardant materials and fire retardant gradually extremely people.Hydrogen Magnesium oxide is a kind of new filled-type fire retardant, and decomposes are absorbed heat and discharged water outlet thus reaching fire-retardant effect.Because of its tool There is nontoxic, low cigarette, do not produce secondary pollution, magnesium hydroxide is a kind of good polymer composites materials of application prospect Inorganic fire-retarded filler.

Common magnesium hydroxide is most to be hexagonal structure or amorphous granular, and specific surface area is big, big with the combination interface of matrix, There is very strong cohesiveness, bad dispersibility, there is the trend of secondary agglomeration.When magnesium hydroxide is as flame-retardant additive, matrix The mechanical property of material can decrease.Acicular magnesium hydroxide does not have boundary or grain, and draw ratio is big, and defect is few, in the material point Scattered property is good, and because of its pattern feature, the mechanical property as the more common magnesium hydroxide of filler of high polymer has clear improvement.

Prepare at present threadiness or the method for acicular magnesium hydroxide mainly have: one, direct precipitation method (cn102050473a, Cn1752004, cn101045869, Liu Jiaxiang, prepare fibrous nano mg (oh) using carbonization-sedimentation method₂Research [periodical Paper])；2nd, presoma conversion method (cn1884633, Wang Congzhuo, the fibrous hydroxide of basic magnesium chloride preparation in ethanol system The technique [journal article] of magnesium, cn1458066a), such as cn1458066a, is by the magnesite of calcining and sulphuric acid or magnesium sulfate After solution Hydrothermal Synthesiss alkali magnesium sulfate, there is the magnesium hydrate powder of certain draw ratio with alkali reaction preparation.To reaction environment Have high demands and technological process is complicated, environment is had an impact.

A lot of relevant reports have been done in the research that magnesium hydroxide is prepared to aquation method by this seminar, such as: money Potiria pectinifera (Mukller et Tro Sehel) etc. A kind of preparation method patent (China, cn201110336270.6 [p], 2012-6-20) of the hexagonal sheet magnesium hydroxide of invention； The magnesium salt of the reports such as Wang Fei and crystal seed magnesium oxide aquation is synthesized the impact of magnesium hydroxide (Chinese powder technology, 2013,19 (2): 40-43), but above-mentioned work is mainly and studies the preparation of hexagonal sheet magnesium hydroxide and the aquation rate of magnesium oxide, be also not directed to low Warm water method directly prepares acicular magnesium hydroxide.

Content of the invention

The invention aims to improving the deficiencies in the prior art and providing a kind of simple and environmentally-friendly, oxidation that yield is high The method that magnesium hydration method prepares acicular magnesium hydroxide.

The technical scheme is that the method preparing acicular magnesium hydroxide, it specifically comprises the following steps that

A) magnisite calcining, prepares light calcined magnesia；

B) light calcined magnesia, magnesium salt, water, dispersant are in mass ratio 1:(0.02～4.5): (10～100): (0.05 ～0.5), mix homogeneously, obtains suspension, by suspension ultrasonic disperse, under agitation, in 60 DEG C～90 DEG C of thermostatted water Bath reaction, after reaction 2～6h, adds crystal seed；

C) reactant liquor that step b) is added crystal seed is aged at room temperature；

D) in step c), product, through filtering, washing, be dried, obtains acicular magnesium hydroxide.

Calcining heat in preferred steps a) is 600 DEG C～1050 DEG C, and calcination time is 2～6h.Super in preferred steps b) Sound jitter time is 5～20min.

Preferably above-mentioned dispersant is Polyvinylpyrrolidone, cetyl trimethylammonium bromide, PEG-400 Or one or more of ethylenediamine.

Preferably above-mentioned crystal seed is basic magnesium chloride whisker, alkali magnesium sulfate crystal whisker or magnesium hydroxide crystal whisker.Preferably crystal seed Addition be light calcined magnesia quality 0.8%～50%.

Aging Temperature in preferred steps c) is 5 DEG C～35 DEG C, and digestion time is 0.5～10 day.

Baking temperature in preferred steps d) is 90～110 DEG C, and drying time is 4～7 hours.

Beneficial effect:

Abundant raw material of the present invention, simple to operate, be not related to strong acid and strong base environmentally safe, easily-controlled reaction conditions；Can Carry out large-scale production；Low temperature hydrated reaction, energy efficient.

The present invention can prepare the needle-like hydroxide of different draw ratios by changing addition and the species of dispersant Magnesium；

The acicular magnesium hydroxide of present invention preparation can recycle as crystal seed, cost-effective.

Activated magnesia is obtained for raw material calcining with magnesite, magnesium oxide prepares acicular magnesium hydroxide through low temperature hydrated, no Only make full use of the resource of China's magnesite, and technological process is simple, easy to operate, environmentally safe, there is good warp Ji benefit and social benefit.

Brief description

Fig. 1 prepares the xrd collection of illustrative plates of fibrous magnesium hydroxide for the present invention；

Fig. 2 is the microscope figure of embodiment 1 products therefrom；

Fig. 3 is the microscope figure of embodiment 2 products therefrom；

Fig. 4 is the microscope figure of embodiment 3 products therefrom；

Fig. 5 is the microscope figure of embodiment 4 products therefrom；

Fig. 6 is the microscope figure of embodiment 5 products therefrom.

Specific embodiment

Embodiment 1

Weigh magnesium oxide 2g after 700 DEG C of calcining 6h for the magnesite, add 0.16g Polyvinylpyrrolidone, 0.16g 16 Alkyl trimethyl ammonium bromide, 0.8g magnesium sulfate and 50ml water are made into aqueous solution, ultra-dispersed 5min, react 6h in 80 DEG C of stirring in water bath Afterwards, add 0.96g magnesium hydroxide crystal whisker crystal seed, react 8min, stopped reaction, at 6 DEG C be aged 9 days, through filter, washing, 90 DEG C 6h is dried, obtains acicular magnesium hydroxide.The mg (oh) generating₂The xrd of crystal as shown in figure 1, as seen from Figure 1, the spreading out of generation Penetrate peak to match with magnesium hydroxide jcpds86-2164 standard card, free from admixture.Fig. 2 is the microscope figure of this example products therefrom Piece, the magnesium hydroxide generating as can be seen from Figure 2 is needle-like, there is a small amount of threadiness, and major diameter is 160 μm～1100 μm.

Embodiment 2

Weigh magnesium oxide 4g after 950 DEG C of calcining 4h for the magnesite, add 0.61g PEG-400,0.2ml second two Amine, 6.26g magnesium sulfate and 200ml water are made into aqueous solution, ultra-dispersed 10min, after 90 DEG C of stirring in water bath react 2h, add 1.02g basic magnesium chloride crystal seed, reacts 10min, stopped reaction, is aged 8 days at 12 DEG C, through filtration, washing, 100 DEG C of dryings 4h, obtains acicular magnesium hydroxide.Fig. 3 is the microscope photograph of this example products therefrom, and the magnesium hydroxide generating as can be seen from Figure 3 is Needle-like, major diameter is 70 μm～300 μm.

Embodiment 3

Weigh magnesium oxide 4g after 1050 DEG C of calcining 2h for the magnesite, add 7.98g magnesium sulfate and 350ml water, 1.2ml second Diamidogen is made into aqueous solution, ultra-dispersed 12min, after 85 DEG C of stirring in water bath react 4h, interpolation 0.38g alkali magnesium sulfate crystal seed, and 30 DEG C ageing 2 days, through filter, washing, 105 DEG C 4h is dried, obtain acicular magnesium hydroxide.Fig. 4 is the microscope of this example products therefrom Picture, the magnesium hydroxide generating as can be seen from Figure 4 is needle-like, and major diameter is 90 μm～600 μm.

Embodiment 4

Weigh magnesium oxide 6g after 950 DEG C of calcining 4h for the magnesite, add 3g PEG-400,0.126g magnesium sulfate It is made into aqueous solution with 90ml water, ultra-dispersed 8min, after 90 DEG C of stirring in water bath react 2h, adds 0.05g magnesium hydroxide crystal whisker brilliant Kind, react 8min, stopped reaction, at 10 DEG C be aged 0.5 day, through filter, washing, 105 DEG C 6h is dried, obtain needle-like hydroxide Magnesium.Fig. 5 is the microscope photograph of this example products therefrom, and the magnesium hydroxide generating as can be seen from Figure 5 is needle-like, exists fan-shaped simultaneously Magnesium hydroxide, major diameter is 70 μm～750 μm.

Embodiment 5

Weigh magnesium oxide 2g after 1050 DEG C of calcining 2h for the magnesite, add 0.1g Polyvinylpyrrolidone, 0.1g 16 Alkyl trimethyl ammonium bromide, 8.92g magnesium sulfate and 180ml water are made into aqueous solution, ultra-dispersed 12min, anti-in 60 DEG C of stirring in water bath After answering 6h, add 1g magnesium hydroxide crystal whisker crystal seed, react 12min, stopped reaction, be aged 10 days at 25 DEG C, through filtering, washing Wash, 90 DEG C 5h is dried, obtain acicular magnesium hydroxide.Fig. 6 is the microscope photograph of this example products therefrom, generates as can be seen from Figure 6 Magnesium hydroxide be needle-like, but there is double-helix and sector, major diameter is 50 μm～740 μm.

Claims

1. the method preparing acicular magnesium hydroxide, it specifically comprises the following steps that

A) magnisite calcining, prepares light calcined magnesia；

B) light calcined magnesia, magnesium sulfate, water, dispersant are in mass ratio 1:(0.02～4.5): (10～100): (0.05～ 0.5), mix homogeneously, obtains suspension, by suspension ultrasonic disperse, under agitation, in 60 DEG C～90 DEG C of water bath with thermostatic control Reaction, after reaction 2～6h, adds crystal seed；Wherein said dispersant is Polyvinylpyrrolidone, cetyl trimethyl bromination One or more of ammonium, PEG-400 or ethylenediamine；Described crystal seed is basic magnesium chloride whisker, alkali magnesium sulfate is brilliant Palpus or magnesium hydroxide crystal whisker；

2. in accordance with the method for claim 1, calcining heat in step a) for its feature is 600 DEG C～1050 DEG C, calcining Time is 2～6h.

3. in accordance with the method for claim 1 it is characterised in that the addition of crystal seed be light calcined magnesia quality 0.8%～ 50%.

4. in accordance with the method for claim 1 it is characterised in that the Aging Temperature in step c) is 5 DEG C～35 DEG C, during ageing Between be 0.5～10 day.

5. in accordance with the method for claim 1 it is characterised in that the baking temperature in step d) is 90～110 DEG C, when being dried Between be 4～7 hours.